There are known devices for the cutting of submerged structures which operate with fixed blades, such as the one described for example in the document U.S. Pat. No. 3,056,267, or provided with several rotary blades co-ordinated in their action as in the document U.S. Pat. No. 4,180,047. Both apparatus however present the disadvantage of operating only on the emerging and free end of the submerged structure.
In the document EP-B-0 540 834, owned by the same applicant, there is described a method and a device for cutting underwater structures which make use of a diamond cable as cutting means; the device permits the cutting of the underwater structure at any level comprised between the bottom end and the surface.
Presently, the new provisions which are in force practically everywhere, and which are extremely more severe as for what concerns the environmental impact, require that the cutting of the submerged structures cannot be effected by leaving the residual stump of the structure emerging from the (sea) bottom, but instead by effecting the cut below the level of the bottom itself. Under these conditions, by utilising the presently available means, it results necessary to remove a relevant quantity of sea bottom around the base of the structure to be cut. This further operation, besides being costly, is frequently damaging as for what concerns the environment, which on the contrary this type of “underground” cutting would tend to safeguard.